Have we just found out how bad Xbox sales are?

The chief executive CEO of an eSports company might have let slip that Microsoft may have sold only half the number of games consoles as its rival Sony.

In a press release published this week announcing a new app for Microsoft's Xbox One that will allow players to compete more easily online, Neville Upton, chief executive officer of Gfinity, implied there were around 18 million owners of the games console.

"We are delighted to announce the launch of our Tournament Builder App on Xbox One which will enhance the Gfinity offering and enable us to reach Xbox One's 18 million users globally," he said in the release.

Sony's PlayStation 4 has substantially outsold Microsoft's Xbox One
Olly Curtis | Future Publishing | Getty Images
Sony's PlayStation 4 has substantially outsold Microsoft's Xbox One

If this is correct, it means the Sony PlayStation 4 has substantially outsold its rival. In March, Andrew House, president and CEO of Sony Computer Entertainment, said Sony had sold 36 million PS4 consoles since it launched in November 2013.

Microsoft, meanwhile, has not issued a sales figure update since November 2014. The company did not respond to requests for comment at the time of publication.

However, Gfinity later said that it did not have access to Microsoft's sales figures and was basing its estimates on other source.

"Gfinity would like to clarify that it has not sought to confirm Microsoft sales figures," the company said in a statement to CNBC. "The comments in yesterday's statement are based on a variety of independent sources published earlier this year."

The figure of 18 million tallies with previous estimates made by different individuals, including Electronic Arts CFO Blake Jorgensen who, during a financial conference in January, implied that around 18 to 19 million Xbox consoles had been sold.

Steve Bailey, senior games analyst at IHS technology, explained to CNBC why Microsoft's console was so far behind in terms of sales.

"The Xbox has been lagging behind the PS4 since its inception, ever since both launched at the end of 2013," he told CNBC via email. "There were a variety of reasons for this, including Xbox One's higher pricing and its compulsory bundling with Kinect.

"Not to mention, the PlayStation brand has much stronger traction in both Europe and Japan that Xbox hasn't supplanted."

According to Bailey, the Xbox One has managed to maintain the sales gap and not let it grow by releasing regular software updates and cultivating strong game releases, but doesn't expect the gap to be closed any time soon.

Meanwhile, Paolo Pescatore, director of multiplay and media at CCS Insight, said that the news reinforces its view that the Xbox One and PlayStation 4 will fail to match the sales achieved by previous console generations.

"Manufacturers have tried to broaden the appeal of such devices by repurposing them as general media hubs and, as a result of this, costs have risen and it will fail to attract core users," he told CNBC via email.

Pescatore expects console gaming to further diminish as gaming shifts to mobile platforms.

"Game publishers have accelerated their plans to make a greater number of major titles available across mobile platforms," he said. "We still expect to see over time that dedicated games consoles will cease to exist as a distinct category.

Follow CNBC International on Twitter and Facebook.